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git.ipfire.org Git - thirdparty/git.git/blob - delta.h
4 /* opaque object for delta index */
8 * create_delta_index: compute index data from given buffer
10 * This returns a pointer to a struct delta_index that should be passed to
11 * subsequent create_delta() calls, or to free_delta_index(). A NULL pointer
12 * is returned on failure. The given buffer must not be freed or altered
13 * before free_delta_index() is called. The returned pointer must be freed
14 * using free_delta_index().
17 create_delta_index(const void *buf
, unsigned long bufsize
);
20 * free_delta_index: free the index created by create_delta_index()
22 * Given pointer must be what create_delta_index() returned, or NULL.
24 void free_delta_index(struct delta_index
*index
);
27 * sizeof_delta_index: returns memory usage of delta index
29 * Given pointer must be what create_delta_index() returned, or NULL.
31 unsigned long sizeof_delta_index(struct delta_index
*index
);
34 * create_delta: create a delta from given index for the given buffer
36 * This function may be called multiple times with different buffers using
37 * the same delta_index pointer. If max_delta_size is non-zero and the
38 * resulting delta is to be larger than max_delta_size then NULL is returned.
39 * On success, a non-NULL pointer to the buffer with the delta data is
40 * returned and *delta_size is updated with its size. The returned buffer
41 * must be freed by the caller.
44 create_delta(const struct delta_index
*index
,
45 const void *buf
, unsigned long bufsize
,
46 unsigned long *delta_size
, unsigned long max_delta_size
);
49 * diff_delta: create a delta from source buffer to target buffer
51 * If max_delta_size is non-zero and the resulting delta is to be larger
52 * than max_delta_size then NULL is returned. On success, a non-NULL
53 * pointer to the buffer with the delta data is returned and *delta_size is
54 * updated with its size. The returned buffer must be freed by the caller.
57 diff_delta(const void *src_buf
, unsigned long src_bufsize
,
58 const void *trg_buf
, unsigned long trg_bufsize
,
59 unsigned long *delta_size
, unsigned long max_delta_size
)
61 struct delta_index
*index
= create_delta_index(src_buf
, src_bufsize
);
63 void *delta
= create_delta(index
, trg_buf
, trg_bufsize
,
64 delta_size
, max_delta_size
);
65 free_delta_index(index
);
72 * patch_delta: recreate target buffer given source buffer and delta data
74 * On success, a non-NULL pointer to the target buffer is returned and
75 * *trg_bufsize is updated with its size. On failure a NULL pointer is
76 * returned. The returned buffer must be freed by the caller.
78 void *patch_delta(const void *src_buf
, unsigned long src_size
,
79 const void *delta_buf
, unsigned long delta_size
,
80 unsigned long *dst_size
);
82 /* the smallest possible delta size is 4 bytes */
83 #define DELTA_SIZE_MIN 4
86 * This must be called twice on the delta data buffer, first to get the
87 * expected source buffer size, and again to get the target buffer size.
89 static inline unsigned long get_delta_hdr_size(const unsigned char **datap
,
90 const unsigned char *top
)
92 const unsigned char *data
= *datap
;
93 unsigned long cmd
, size
= 0;
97 size
|= (cmd
& 0x7f) << i
;
99 } while (cmd
& 0x80 && data
< top
);